Play a champion for the role you're assigned.
Long story short: I wish people would be more open-minded to other roles and play appropriate champs for those roles.
Had someone who, after I had already locked in as
ADC, decided to lock in
, said, "I won't support," and started farming when we got in lane. I asked them to stop and they said, "I play ADC, not supp." I left because they wouldn't even consider taking a different champ during champ select and then refused to actually sit back and be the support (not that hard, it's my main role). Shitty on my part to leave, but there was no way that game was going to go well whatsoever, and I told the team go ahead and report me, I'll take the LeaveBuster.
I wish people would become more well-rounded, and give other roles a chance, and with that comes playing a proper champion for that role. Playing a role and/or champion you aren't used to can be scary/awful/horrible etc., BUT don't pick an obviously bad choice for that role if you happen to get one you're not the best at. Just say, "Hey, I've never played this role/champ before bare with me." I know it happens to everyone, hell, I ask to trade jg a lot, but if I get stuck in the jg, I'll tell the team, just be ready for me to suck, I don't take
into the jg and expect to do well.
**This was in norms. I rarely see anyone pull this during ranked because in champ select, the team will actually make sure (for the most part) that everyone is in a role they're comfortable with.